Change in Intraocular Pressure after Selective Laser Trabeculoplasty in North Indian Primary Open Angle Glaucoma Patients: A Prospective Analytical Study

Abstract

Introduction: Glaucoma is the second leading cause of blindness in the world. The only known modifiable risk factor for the onset and progression of glaucoma is Intraocular Pressure (IOP). There are a limited number of studies documenting the IOP-lowering effect of Selective Laser Trabeculoplasty (SLT) in Primary Open Angle Glaucoma (POAG) patients, especially within the North Indian population. Understanding the effect of SLT on IOP reduction in this population is crucial for the proper management of glaucoma patients. Aim: To study the IOP-lowering effect of SLT in North Indian POAG patients (who had not achieved target IOP on two or more antiglaucoma drugs) after a period of six months. Materials and Methods: A hospital-based, single-arm, prepost type of prospective analytical study was conducted at Lady Hardinge Medical College and associated hospitals in New Delhi, India, from January 2021 to June 2022. POAG patients aged 18 years or older, who had not achieved the target IOP while on two or more Antiglaucoma Medications (AGM), were given the option of treatment with SLT. A total of 33 eyes were considered for the study as per sample size calculations. PreSLT, IOP was recorded along with other baseline parameters. The SLT procedure was carried out according to the standard protocol. IOP was recorded during follow-ups at one week, one month, three months, and six months. The Friedman test was used to compare IOP values, with a significance level set at 0.05. Spearman correlation was employed to explore the correlation between baseline IOP and the change in IOP at six months. Results: A total of 33 eyes were included in the study. Of these, 28 (84.8%) eyes had advanced glaucoma, while 5 (15.2%) eyes had moderate glaucoma according to International Classification of Diseases, Tenth Revision (ICD-10) staging. Patients were on two or more commonly used AGMs, including prostaglandin analogues, beta blockers, alpha agonists, topical carbonic anhydrase inhibitors, and rho kinase inhibitors. The mean number of topical AGMs that patients were using was 3.03. The number and type of AGMs for each patient remained consistent pre and post-SLT throughout the study period. The mean IOP (baseline) was 16.39±2.73 mmHg, and after six months, the mean IOP was 13.86±1.99 mmHg. The mean IOP reduced by 2.53 mm Hg (15.44%). There was a strong negative correlation between baseline IOP and the change in IOP at six months, which was statistically significant (rho=-0.78, p-value<0.001). Conclusion: The present study indicates that SLT can be considered an adjunctive treatment for lowering IOP in North Indian POAG patients. A strong negative correlation was found between baseline IOP and IOP at six months post-SLT, suggesting that a higher reduction can be expected in patients with elevated baseline IOP.